DeferredRequestInit

Limited availability

The DeferredRequestInit dictionary of the Fetch API represents the set of options that can be used to configure a deferred fetch request.

The DeferredRequestInit object is passed directly into the fetchLater() function call as the second argument.

Instance properties

This dictionary extends the RequestInit dictionary with the addition of the following properties:

• activateAfter Optional
  • : A DOMHighResTimeStamp indicating a timeout in milliseconds after which the fetch request should be sent. The fetch can be sent earlier on navigating away. The actual sending time is unknown, as the browser may wait for a longer or shorter time, for example, to optimize the batching of deferred fetches. If the activateAfter property is not provided, the deferred fetch waits until the end of the page visit (including entering the bfcache).

Exceptions

• RangeError DOMException
  • : Raised when a negative activateAfter is provided.

Examples

Defer a GET request until the page is destroyed or enters the bfcache

In this example, no DeferredRequestInit object is provided and no timeout is used:

fetchLater("/send_beacon");

Defer a POST request for around 1 minute

In this example we create a Request, and provide an activateAfter value to delay sending the request for 60,000 milliseconds (or one minute):

fetchLater("/send_beacon", {
  method: "POST",
  body: getBeaconData(),
  activateAfter: 60000, // 1 minute
});

[!NOTE] The actual sending time is unknown, as the browser may wait for a longer or shorter period of time, for example to optimize batching of deferred fetches.

Specifications

Browser compatibility

See also

• Using Deferred Fetch
• ServiceWorker API
• HTTP access control (CORS)
• HTTP